Thats confusing, but, like I have a problem that says "find the approximate rate of change between 1970 and 1975." And on the graph, the numbers for those years are 50 and 110. So I divided them like you said? :o

in a way, yes; but becasue these dont intersect with the (0,0) we can be sure that they are moving in sync like that
it is best to divide the change between them instead
1970 to 1975 is a change of 5
50 to 110 is a change of 60
therefore we can say for certain that the rate of change is 60/5

Yeah its confusing :P like I have another one, its rate of change between 1995 and 2000. Im just kinda going with the effect of what you said ...idk if im right, but approximately 2000 divided by 1995 is 1.003, and 690 divided by 600 (the numbers for those years on the graph) is 1.3...so what, 1.003/1.3?? Confusedd :P